173 research outputs found

    Positioning in Indoor Mobile Systems

    Get PDF
    Non

    Introduction of the composite materials and applications for manufacturing technology

    Get PDF
    A composite material can be defined as a combination of two materials resulting in better properties than those of the individual's compound used. The two constituents form a matrix and reinforcement. the main advantages of composite materials are their high strength and rigidity, combined with low density compared with bulk materials, which allows a reduction in weight in the finished part..

    Digital Beamforming Techniques for Passive UHF RFID Tag Localization

    Get PDF
    Radio-frequency identification (RFID) technology is on the way to substitute traditional bar codes in many fields of application. Especially the availability of passive ultra-high frequency (UHF) RFID transponders (or tags) in the frequency band between 860 MHz and 960 MHz has fostered the global application in supply chain management. However, the full potential of these systems will only be exploited if the identification of objects is complemented by accurate and robust localization. Passive UHF RFID tags are cost-effective, very small, extremely lightweight, maintenancefree, rugged and can be produced as adhesive labels that can be attached to almost any object. Worldwide standards and frequency regulations have been established and a wide infrastructure of identification systems is operated today. However, the passive nature of the technology requires a simple communication protocol which results in two major limitations with respect to its use for localization purposes: the small signal bandwidth and the small allocated frequency bandwidth. In the presence of multipath reflections, these limitations reduce the achievable localization accuracy and reliability. Thus, new methods have to be found to realize passive UHF RFID localization systems which provide sufficient performance in typical multipath situations. In this thesis, an enhanced transmission channel model for passive UHF RFID localization systems has been proposed which allows an accurate estimation of the channel behaviour to multipath. It has been used to design a novel simulation environment and to identify three solutions to minimize multipath interference: a) by varying the channel interface parameters, b) by applying diversity techniques, c) by installation of UHF absorbers. Based on the enhanced channel model, a new method for tag readability prediction with high reliability has been introduced. Furthermore, a novel way to rate the magnitude of multipath interference has been proposed. A digital receiver beamforming localization method has been presented which uses the Root MUSIC algorithm for angulation of a target tag and multipath reducing techniques for an optimum localization performance. A new multiangulation algorithm has been proposed to enable the application of diversity techniques. A novel transmitter beamforming localization approach has been presented which exploits the precisely defined response threshold of passive tags in order to achieve high robustness against multipath. The basic technique has been improved significantly with respect to angular accuracy and processing times. Novel experimental testbeds for receiver and transmitter beamforming have been designed, built and used for verification of the localization performance in real-world measurements. All the improvements achieved contribute to an enhancement of the accuracy and especially the robustness of passive UHF RFID localization systems in multipath environments which is the main focus of this researc

    A study of RF-over-fibre based active RFID indoor location system

    Get PDF
    Location systems developed for indoor environments have attracted increasing interest, as a result of the rapidly growing location and navigation services provided by the Global Positioning System (GPS). Location information of people and objects can be used to cooperate with existing communication or database systems to provide abundant services to system operators and end users. For example, equipment tracking in hospitals ensure that location of the appropriate equipment can be provided simultaneously with necessary medical services; attendee tracking at conferences may encourage more efficient communications and networking; location of valuable assets in factories or warehouses aids logistics and protects these assets from theft. Since established global and terrestrial navigation systems cannot provide reliable location services in indoor environments, these demands are increasingly being met by wireless indoor location systems. A review of the existing systems reveals that the current systems are able to provide either an accurate location service with sophisticated system design at higher cost or a less accurate location service by means of integrated systems supplemented by existing facilities. This thesis presents a novel design of an indoor location system that is based on an RF-over-fibre backbone network, which is able to provide high location accuracy while the network infrastructure can be shared with multiple wireless systems. It is the first such demonstrator in this area. This research has been conducted by the author through a research project called The Intelligent Airport (TINA), which is the motivation for this research. The TINA project seeks to develop a new seamless wireless/wired ubiquitous infrastructure with high levels of computational capability to meet the application requirements of future airport environments. In the TINA system, multiple wireless services are provided through an integrated system supported by an RF-over-Fibre network, which transports RF signals through optical fibres. The active RFID indoor location unit is an essential part of the TINA system, which will facilitate the infrastructure to provide location-based services. The thesis describes the detailed design of the active RFID indoor location system proposed for the TINA project, and a few key issues discovered during trials of the demonstration system developed. The overall system design, including ranging technique, TDOA location finding algorithm, and hardware implementation, is presented in this thesis. Particular contributions also include a numerical algorithm for solving target location from TDOA measurement and a technique to determine the chirp linearity requirement. The field trial results of the system design demonstrate the principals and their location performance. The system has the potential to be extended to other scenarios where RF-over-fibre networks are employed and accurate location ability is desired

    A State-of-the-Art Survey of Indoor Positioning and Navigation Systems and Technologies

    Get PDF
    The research and use of positioning and navigation technologies outdoors has seen a steady and exponential growth. Based on this success, there have been attempts to implement these technologies indoors, leading to numerous studies. Most of the algorithms, techniques and technologies used have been implemented outdoors. However, how they fare indoors is different altogether. Thus, several technologies have been proposed and implemented to improve positioning and navigation indoors. Among them are Infrared (IR), Ultrasound, Audible Sound, Magnetic, Optical and Vision, Radio Frequency (RF), Visible Light, Pedestrian Dead Reckoning (PDR)/Inertial Navigation System (INS) and Hybrid. The RF technologies include Bluetooth, Ultra-wideband (UWB), Wireless Sensor Network (WSN), Wireless Local Area Network (WLAN), Radio-Frequency Identification (RFID) and Near Field Communication (NFC). In addition, positioning techniques applied in indoor positioning systems include the signal properties and positioning algorithms. The prevalent signal properties are Angle of Arrival (AOA), Time of Arrival (TOA), Time Difference of Arrival (TDOA) and Received Signal Strength Indication (RSSI), while the positioning algorithms are Triangulation, Trilateration, Proximity and Scene Analysis/ Fingerprinting. This paper presents a state-of-the-art survey of indoor positioning and navigation systems and technologies, and their use in various scenarios. It analyses distinct positioning technology metrics such as accuracy, complexity, cost, privacy, scalability and usability. This paper has profound implications for future studies of positioning and navigation

    Location tracking in indoor and outdoor environments based on the viterbi principle

    Get PDF

    Angle of Arrival Estimation Utilising Frequency Diverse Radio Antenna Arrays

    Get PDF
    The purpose of this research is to investigate a novel way of combining carrier signals that are transmitted successively over Multiple Frequencies (MF) and traditional metrics to improve AoA estimation. Every signal contains three metrics, amplitude, phase, and frequency. To achieve localisation, current systems utilise the metrics of amplitude (also known as Received Signal Strength (RSS)) and phase that resolves the AoA. However, the metric of frequency is mostly used with Orthogonal Frequency-Division Multiplexing (OFDM) to increase the number of RSS and AoA metrics, which is not optimal. This research answers two questions. Can the use of MF improve AoA estimation? Also, how can MF and traditional metrics be combined for AoA estimation? The aim is to prove that the metric of frequency can be utilised more optimally. Therefore, measurements of RSS and AoA are performed in different environments for MF. To perform these measurements, ten frequency diverse Software Defined Radios (SDRs) are employed. A novel technique to time/frequency synchronise the SDRs is developed and presented. Moreover, a ten element Uniform Linear Array (ULA) is designed, simulated and manufactured. The outcomes of this research are two novel algorithms for the MF AoA estimation of a carrier transmitter. Findings of the first algorithm show that the use of MF with the RSS metric performs equally with current systems that have a higher cost and complexity. The second algorithm that utilises MF with the AoA metric demonstrates a significant reduction in the AoA estimation error, compared to current systems. Specifically, for 50\% of the measured cases the AoA estimation error is reduced by 3.7 degrees, while for 95\% of the measured cases the AoA estimation error is reduced by 27 degrees. Hence, this research proves that MF with traditional metrics can reduce system complexity and greatly improve AoA estimation
    • …
    corecore